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An Experimental Investigation Of Pressure Dependent And Time Dependent Fracture Aperture And Permeability In Barnett Shale
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Book Synopsis An Experimental Investigation of Pressure-dependent and Time-dependent Fracture Aperture and Permeability in Barnett Shale by : Yin Gong
Download or read book An Experimental Investigation of Pressure-dependent and Time-dependent Fracture Aperture and Permeability in Barnett Shale written by Yin Gong and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evidence of Pressure Dependent Permeability in Long-Term Shale Gas Production and Pressure Transient Responses by : Fabian Elias Vera Rosales
Download or read book Evidence of Pressure Dependent Permeability in Long-Term Shale Gas Production and Pressure Transient Responses written by Fabian Elias Vera Rosales and published by . This book was released on 2013 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current state of shale gas reservoir dynamics demands understanding long-term production, and existing models that address important parameters like fracture half-length, permeability, and stimulated shale volume assume constant permeability. Petroleum geologists suggest that observed steep declining rates may involve pressure-dependent permeability (PDP). This study accounts for PDP in three potential shale media: the shale matrix, the existing natural fractures, and the created hydraulic fractures. Sensitivity studies comparing expected long-term rate and pressure production behavior with and without PDP show that these two are distinct when presented as a sequence of coupled build-up rate-normalized pressure (BU-RNP) and its logarithmic derivative, making PDP a recognizable trend. Pressure and rate field data demonstrate evidence of PDP only in Horn River and Haynesville but not in Fayetteville shale. While the presence of PDP did not seem to impact the long term recovery forecast, it is possible to determine whether the observed behavior relates to change in hydraulic fracture conductivity or to change in fracture network permeability. As well, it provides insight on whether apparent fracture networks relate to an existing natural fracture network in the shale or to a fracture network induced during hydraulic fracturing. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148240
Book Synopsis Effects of Pressure-dependent Natural-fracture Permeability on Shale-gas Well Production by : Younki Cho
Download or read book Effects of Pressure-dependent Natural-fracture Permeability on Shale-gas Well Production written by Younki Cho and published by . This book was released on 2012 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Investigation of Water Saturation Effects on Barnett Shale's Geomechanical Behaviors by : Shuhua Lin
Download or read book Experimental Investigation of Water Saturation Effects on Barnett Shale's Geomechanical Behaviors written by Shuhua Lin and published by . This book was released on 2012 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Investigation Of Effective Matrix Permeability And The Effect Of Soaking Time In Ultra-tight Shales by : Nirjhor Chakraborty
Download or read book Experimental Investigation Of Effective Matrix Permeability And The Effect Of Soaking Time In Ultra-tight Shales written by Nirjhor Chakraborty and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid flow behavior through ultra-tight shale matrices is still poorly understood. Applications of classical concepts to these unconventional materials are proving to be insufficient and there is a need to generate data on the fundamental processes of fluid transport through nano-porosity networks. This work attempts to address this issue through an array of flow and materials characterization experiments. The context of this integrated petrophysical analysis is the examination of the impact of fluid leakoff and post stimulation shut-in or "soaking time" on effective gas permeability. Past research on fluid leakoff and soaking time has been predominantly conducted with relatively high permeability rocks and for short durations of up to 15 days. We present data on shales with nano-Darcy (10-6 md) permeability and have run experiments for up to 30 days. A pulse-decay permeability apparatus has been custom designed to accurately measure gas permeabilities down to 1nD and the results have been scrutinized in conjunction with X-Ray CT, SEM imaging, Mercury Porosimetry and XRD analysis. Results indicate that laminations and micro-fractures play an important role in fluid transport properties in these ultra-tight shales. There appears to be very little connected porosity at scales longer than a few millimeters, making clastic permeability virtually non-existent. The consequences of fluid leakoff are severe and the introduction of relatively small quantities of liquid into the rock matrix leads to orders of magnitude reductions in effective permeability. The impact of this leakoff fluid then evolves significantly as it is spontaneously redistributed through the rock matrix due to capillary imbibition. Base permeability or the initial absolute (single phase) permeability of dry sample is found to be key to understanding the consequences of soaking time -- high permeability samples experience relatively minor permeability impairment due to leakoff and permeability recovery with soaking time while tighter samples experience permeability damage greater than 90% due to leakoff which continues to decline with soaking time. This raises the strong possibility that the practice of soaking in shale gas wells may be detrimental to long term production and ultimate recovery.
Book Synopsis Experimental Investigation of Matrix Permeability of Shale by : Ashish Mathur
Download or read book Experimental Investigation of Matrix Permeability of Shale written by Ashish Mathur and published by . This book was released on 2015 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Unconventional Reservoir Geomechanics by : Mark D. Zoback
Download or read book Unconventional Reservoir Geomechanics written by Mark D. Zoback and published by Cambridge University Press. This book was released on 2019-05-16 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the key geologic, geomechanical and engineering principles that govern the development of unconventional oil and gas reservoirs. Covering hydrocarbon-bearing formations, horizontal drilling, reservoir seismology and environmental impacts, this is an invaluable resource for geologists, geophysicists and reservoir engineers.
Book Synopsis A Framework for the Prediction of Long-term Time-dependent Deformation of Shale by : Qing Yin
Download or read book A Framework for the Prediction of Long-term Time-dependent Deformation of Shale written by Qing Yin and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The long-term creep behavior of shale has become a major concern in different engineering applications, which reduces oil and gas production of shale reservoirs and triggers devastating landslides. While indentation creep tests at the nanoscale can reveal creep responses of single-material phases within minutes, long-term experimental studies on the bulk shale samples that last months to years are still limited by their time-consuming nature. Meanwhile, numerical studies on this subject are restricted to empirical formulations, creating little connection to the microstructures of the material. In this work, a framework for predicting the long-term creep behavior of shale is proposed based on a novel constitutive formulation, which bridges the creep response of the bulk shale sample at the centimeter scale and the mechanical properties of single-material phases at the sub-micron scale. The constitutive law developed in this work incorporates three material properties: heterogeneity, anisotropy, and viscoplasticity. Based on experimental results, the constitutive law considers a simplified two-material mixture of a softer phase representing clay and organics, and a harder phase representing inorganic matter. This setting captures two levels of heterogeneity: (1) the two-material mixture at one point representing the volume-average of the sub-micron scale heterogeneity, and (2) the variation of volume fractions from point to point representing the mesoscale heterogeneity in a centimeter-scale bulk shale sample. At the same time, it naturally bridges the mechanical responses from nanoscale to centimeter scale. Under the framework of the modified Cam-Clay critical state model, transverse isotropy is incorporated into the harder material and assumed for both elastic and viscoplastic responses. Time-dependent behavior is addressed by the viscoplastic formulations of Duvaut-Lions and Perzyna, which exhibit excellent convergence properties. To demonstrate the features of the constitutive formulations, a finite element package called GeoScale is developed and applied to several numerical examples. A triaxial creep test on the organic-rich Barnett shale is first simulated. While transverse isotropy is only incorporated in the harder material phase, the solution successfully captures the anisotropic creep responses along different directions of the bulk material, which shows a strong agreement with the experimental results. It is worth noting that similar results cannot be replicated by a one-material model with or without anisotropy, which further justifies the necessity of the two-material model. Second, strain localization in the form of dilative shear band is observed in a set of 2D plane strain simulations under a strain-driven approach, in which the different shear band patterns, either conjugate or single-dominating, are shown to result from various strain rates. In this example, it is worth noting that no element enhancement is needed to accommodate the localized deformation, as viscoplasticity in the formulation acts as a form of regularization. Furthermore, a shale sample with spatially varying volume fractions of material phases is loaded under a constant axial stress. It is shown that the proposed model can trigger multiple creep-induced shear bands, which develop along the weaker direction of the sample and grow in width. GeoScale is further extended to simulate indentation tests on Woodford shale at the nanometer and micrometer scales using an incremental frictionless multi-body contact algorithm based on the Lagrange multipliers method, along with our constitutive framework. Simulation results suggest that creep of the sample is mostly attributed to the viscoplastic deformation of the material away from the indenter tip, and that such response is highly dependent on the stress rate during the loading stage. The time-related material properties are calibrated from the nano- and micro-indentation experiments. As the calibrated material properties become available, the long-term creep behavior of shale is predicted by simulating 3D triaxial creep tests, marking the completion of this work.
Book Synopsis Evaluation of Lean and Rich Gas Injection for Improved Oil Recovery in Hydraulically Fractured Reservoirs by : Williams Osagie Ozowe
Download or read book Evaluation of Lean and Rich Gas Injection for Improved Oil Recovery in Hydraulically Fractured Reservoirs written by Williams Osagie Ozowe and published by . This book was released on 2021 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estimating improvements in oil recovery in shales can be difficult, because of their ultra-low permeability - often in the nanodarcy range. In addition, poroelastic changes occurring within the reservoir during production, have a direct impact on porosity and flow paths. Recovery estimates from simulations are imprecise, because inaccurate capillary pressure curves and liquid permeability estimates are often used for forecasting. This work presents a new method to measure liquid saturation and capillary pressure in shales, by integrating the time-dependent pressure drop data observed within the bulk liquid phase, when a shale sample is under liquid pressure. This work also presents an experimental method to estimate liquid permeability in shale, by using the early time portion of the liquid pressure decay data - that has been corrected for temperature effects – to estimate diffusivity, via a graphical approach that approximates the solution of the radial diffusivity equation coupled with the mass balance equation. In unconventional reservoirs it is quite common to experience a rapid decline in production and reservoir pressure during primary production. For this reason, operators have sought to find ways to improve oil recovery via cyclic gas injection in shale reservoirs. To achieve this, it is important to understand the role of fluid compressibility, miscibility, soak time and injection pressure on oil recovery. The choice of these parameters can have a significant impact on recovery factor, the produced gas-oil ratio and economic viability. This work presents results from an experimental study of these properties on Eagle Ford core plugs and crushed samples, via the injection of liquid and gaseous recovery agents at room temperature. Results show that gaseous solvents perform better than liquid solvents and oil recovery increases with injection pressure, and with increasing surface area to volume ratio of the shale samples. To better understand the role of poroelastic changes on oil recovery, cyclic gas injection simulations were conducted in the Eagle Ford shale using a fully coupled compositional, geomechanical hydraulic fracturing and reservoir simulator. Results obtained show that effective stress changes occurring during injection and production cycles in the stimulated reservoir volume results in a decrease in reservoir permeability, and this reduces oil recovery. Also, simulation results between miscible and immiscible gases show that immiscible gases yield lower oil recovery factors and higher gas-oil ratios, than more miscible gases. Finally, from simulation studies carried out for the Bakken and Wolfcamp shales, it was observed that increasing the mole fraction of the heavier molecular weight hydrocarbon gases in the injection gas improves miscibility with the reservoir fluid, and increases oil recovery. Additional results show that this enhanced degree of miscibility of the injection gas with the reservoir fluid, was not impacted by the substitution of low molecular weight hydrocarbons for carbon dioxide in a hybrid injection gas mixture
Book Synopsis Optimization of Hydraulic Fracture Stages and Sequencing in Unconventional Formations by : Ahmed Alzahabi
Download or read book Optimization of Hydraulic Fracture Stages and Sequencing in Unconventional Formations written by Ahmed Alzahabi and published by CRC Press. This book was released on 2018-07-03 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shale gas and/or oil play identification is subject to many screening processes for characteristics such as porosity, permeability, and brittleness. Evaluating shale gas and/or oil reservoirs and identifying potential sweet spots (portions of the reservoir rock that have high-quality kerogen content and brittle rock) requires taking into consideration multiple rock, reservoir, and geological parameters that govern production. The early determination of sweet spots for well site selection and fracturing in shale reservoirs is a challenge for many operators. With this limitation in mind, Optimization of Hydraulic Fracture Stages and Sequencing in Unconventional Formations develops an approach to improve the industry’s ability to evaluate shale gas and oil plays and is structured to lead the reader from general shale oil and gas characteristics to detailed sweet-spot classifications. The approach uses a new candidate selection and evaluation algorithm and screening criteria based on key geomechanical, petrophysical, and geochemical parameters and indices to obtain results consistent with existing shale plays and gain insights on the best development strategies going forward. The work introduces new criteria that accurately guide the development process in unconventional reservoirs in addition to reducing uncertainty and cost.
Book Synopsis Fracture Permeability in Porous Reservoirs by : Ronald A. Nelson
Download or read book Fracture Permeability in Porous Reservoirs written by Ronald A. Nelson and published by . This book was released on 1975 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Influence of Cracks and Microcracks on Flow and Storage Capacities of Gas Shales at Core-level by : Khalid R. Alnoaimi
Download or read book Influence of Cracks and Microcracks on Flow and Storage Capacities of Gas Shales at Core-level written by Khalid R. Alnoaimi and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Economical shale gas production is only possible via hydraulic fracturing in which a fluid is injected in the subsurface at a pressure large enough to penetrate the near wellbore region. Hydraulic fracturing activates subsets of cracks and microcracks that facilitate transfer of gas to exit the matrix. This process creates stress sensitive flow dynamics between various media with their respective flow paths. This complex interplay of transport in media with different size scales poses challenges for modeling. Understanding the mechanisms of flow as the reservoir fluid pressure increases during fracturing or decreases during flow back is key for quantifying the production forecast and the volume of reserves. Gas transport in shales is believed to be driven by complex physical mechanisms including Darcy flow, Knudsen diffusion, and adsorption through fractures, microcracks, and matrix. Understanding the interplay of gas transport in these media at increased pore pressure and constant net effective stress, as well as at increased net effective stress (i.e. during depletion) is the goal of this work. This research work investigates the interplay of gas transport in the cracks, microcracks, and matrix of shale using He and CO2 via transient upstream pressure pulse decay experiments. The cracks and microcracks are natural in the sense no lab pretreatment created them. A novel setup of the pressure pulse decay experiment was used to determine the storage and flow capacities simultaneously. Experimentally, the pressure signals are used to define time-dependent pore volume partitioning between the microcracks and the matrix. A dual continuum simulator is constructed to decouple the flow and storage capacity at early-time pressure where the gas flows simultaneously in both media. This is done via a history-matching process that quantifies the pore volume partitioning of the microcracks and matrix, the permeability in the microcracks, and the diffusivity of gas in the matrix. A series of experiments were conducted at constant net effective stress (500 psi) and increasing net effective stress (500, 1000, 2000 psi) to study the evolution of the pore volume partitioning, the permeability in the microcracks, and the diffusion in the matrix. The experiments were conducted on samples from the Eagle Ford and Haynesville shale plays. Results have shown that the pore volume partitioning in the microcracks in sample 180Ha (Eagle Ford) was between 8 - 24.1% of the total pore volume in all experiments at constant and variable net effective stresses. Sample TWG 1-3 (Haynesville) had a percentage of microcracks between 84.5 - 87.0% of the total pore volume. Sample TWG 3-3 had a microcracks portion between 68.8 - 83.1% of the total pore volume. These proportions were found to be related to the magnitude of permeability and void volumes in the system. The greater the permeability and the smaller the void volumes, the smaller is the microcracks pore volume. Samples 180Ha, TWG 1-3, TWG 3-3 had a liquid permeability of 396.3, 1.63, and 16.59 micro Darcy. The gas transport in the matrix was expressed volumetrically via a "diffusional transport group" parameter. This history-match parameter was found to increase generally with pore pressure at constant net effective stress and decrease with increased net effective stress. The role of adsorption was also investigated using CO2 in the same experimental apparatus and conditions. It was found that the influence of pore volume partitioning is suppressed by the large adsorption capacity in the shale samples. The adsorption capacity was a history-match parameter in the analysis. It was found that adsorption occurs in the microcracks in permeabilities less than 50 micro Darcy along with adsorption in the matrix. For permeabilities greater than that value, adsorption had no importance on microcracks. Adsorption in both media required different adsorption-pressure functions. The CO2 permeability was found to be smaller than the He permeability by a 2-3 factors.
Book Synopsis Multi-frac Propagation in Unconventional Shale by : Nana Kwadwo Sasu Asiamah
Download or read book Multi-frac Propagation in Unconventional Shale written by Nana Kwadwo Sasu Asiamah and published by . This book was released on 2015 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the Zipper-Frac technique has become one of the most widely used stimulation techniques in the oil and gas industry. The efficiency in this technique lies in minimizing stress shadows between adjacent stimulated fractures while maximizing fracture network and surface area in order to increase fluid production. The Zipper-Frac technique stimulates two parallel horizontally drilled wellbores, alternating between perforation clusters, while maintaining pressure in the previously fractured wellbore or perforation cluster. This study analyzes and discusses multi-fracture experiments in the laboratory that mimic Zipper-Frac results in unconventional shale. The experiments were conducted with two intended outcomes: (i) to examine how time-dependent pressure decay limits stress shadow effects and (ii) to investigate fracture complexity developed in Zipper-Fracs. To achieve these objectives, laboratory experiments were conducted on synthetic blocks (gypsum cement) of three layers (hydrostone, plaster and hydrostone, respectively). The experiment was conducted on 12 samples. Six samples were fractured with a pressure hold-up technique, where the in-situ stress after fracturing was above the fracture closure stress (FCS); and the other six were fractured with a pressure bleed-off technique, where the pressure was bled-off below the FCS. The results indicate is that greater well spacing and bleeding off pressure in fractures post-treatment result in longer and straighter fractures, hence minimal stress shadow, while closer well spacing and maintaining pressure in fractures post-treatment caused more non-planar fracture paths and less created fracture length, hence stronger stress shadow. Consequently, it can be inferred that less complexity would result with the bleed-off method, but this gives greater fracture surface area because of the greater achieved lengths.
Book Synopsis Micro-scale Experimental Investigations of Multi-phase Flow Through Fractured Porous Media by : Maziar Arshadi
Download or read book Micro-scale Experimental Investigations of Multi-phase Flow Through Fractured Porous Media written by Maziar Arshadi and published by . This book was released on 2017 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the results of systematic micro-scale experimental investigations of multi-phase flow through fractured rock samples under a wide range of flow conditions. The results of the study have direct applications in fluid flow through fractures in conventional reservoirs and hydraulically-induced fractures in ultra-tight unconventional reservoirs. We generate high-resolution, three-dimensional maps of fluid distribution within a rough-walled fracture and its neighboring matrix using a miniature water-wet, fractured sandstone core sample. These maps along with steady-state pressure drop data are then used to shed light on the dominant flow mechanisms and preferential flow paths through the matrix and fracture domains as well as fluid transfer between them during numerous drainage and imbibition displacement cycles. Due to the topology of the fracture in the medium and the magnitude of the local capillary pressures that are established under varying flow conditions, different flow mechanisms govern the transport of the wetting phase through the fracture and matrix, i.e., fracture layer flow, fracture bulk flow, and advancement through matrix pores. The competition between these transport mechanisms is regulated by the medium as it identifies the flow path with minimum pressure drop from the inlet to the outlet of the hybrid matrix-fracture system. The resulting balance determines the magnitude of fluid transfer experienced by the neighboring matrix and ultimate recovery as a result. In the second category of the experiments, we probe two- and three-phase flow displacement processes in proppant-packed fractured shale samples under varying stress conditions. Three sets of experiments are performed to represent the fluid flow behavior through hydraulic fractures in shale oil, shale gas, and shale gas-condensate reservoirs, respectively. In each set of experiments, we study geomechanical deformation and consequent multi-phase flow factors that reduce effective hydrocarbon permeability that in turn results in early production loss in the above-mentioned unconventional reservoirs. We examine various types of proppants including regular sand, white sand, resin-coated sand, and ISP ceramic. Different packings of the proppants including multi-layer, uniform mono-layer, and non-uniform mono-layer, are also tested under severe closure stress conditions. For the first time, wettability alteration of proppant packs due to severe embedment and deposition of shale organic matter is reported at the pore scale. Significantly improved insight developed in this work can be used to design new proppants to effectively maintain hydraulic conductivity of the fractures for extended period of time.
Book Synopsis An Experimental Investigation of Some Capillary Pressure-relative Permeability Correlations for Sandstone Reservoir Rocks by : Abdulaadem A. Bashir
Download or read book An Experimental Investigation of Some Capillary Pressure-relative Permeability Correlations for Sandstone Reservoir Rocks written by Abdulaadem A. Bashir and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydraulic Fracturing in Unconventional Reservoirs by : Hoss Belyadi
Download or read book Hydraulic Fracturing in Unconventional Reservoirs written by Hoss Belyadi and published by Gulf Professional Publishing. This book was released on 2019-06-18 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic Fracturing in Unconventional Reservoirs: Theories, Operations, and Economic Analysis, Second Edition, presents the latest operations and applications in all facets of fracturing. Enhanced to include today’s newest technologies, such as machine learning and the monitoring of field performance using pressure and rate transient analysis, this reference gives engineers the full spectrum of information needed to run unconventional field developments. Covering key aspects, including fracture clean-up, expanded material on refracturing, and a discussion on economic analysis in unconventional reservoirs, this book keeps today's petroleum engineers updated on the critical aspects of unconventional activity. Helps readers understand drilling and production technology and operations in shale gas through real-field examples Covers various topics on fractured wells and the exploitation of unconventional hydrocarbons in one complete reference Presents the latest operations and applications in all facets of fracturing
Book Synopsis Experimental Study on CH4 Permeability and Its Dependence on Interior Fracture Networks of Fractured Coal Under Different Excavation Stress Paths by :
Download or read book Experimental Study on CH4 Permeability and Its Dependence on Interior Fracture Networks of Fractured Coal Under Different Excavation Stress Paths written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
